How much is the sum of the first (55) natural numbers?
Answer and explanation
Correct answer: 1540
The sum of the first \(n\) natural numbers is \(S_n=\frac{n(n+1)}{2}\). Therefore, \(S_{55}=\frac{55\times56}{2}=55\times28=1540\). Hence, option A is correct. \(1515\) is not the correct sum from \(1\) to \(55\). Exam tip: Cancel 2 with the even factor in \(n(n+1)\) before multiplying.
Frequently asked questions
What is the correct answer to this question?
1540
Why is this the correct answer?
The sum of the first \(n\) natural numbers is \(S_n=\frac{n(n+1)}{2}\). Therefore, \(S_{55}=\frac{55\times56}{2}=55\times28=1540\). Hence, option A is correct. \(1515\) is not the correct sum from \(1\) to \(55\). Exam tip: Cancel 2 with the even factor in \(n(n+1)\) before multiplying.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Sequences and Progressions. Topic: Sum of first n natural numbers.
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